CN103311278B - Fast recovery diode and make the method for this diode - Google Patents

Abstract

A kind of fast recovery diode, comprise a N-type highly doped silicon substrate, one first N-type doping semiconductor layer, one second N-type doping semiconductor layer, a diode anode layer, described first N-type doping semiconductor layer is between the second N-type doping semiconductor layer and N-type highly doped silicon substrate, and the doping content of described first N-type doping semiconductor layer is lower than the doping content of the second N-type doping semiconductor layer.Above-mentioned fast recovery diode can provide enough carrier concentrations when Reverse recovery, thus is maintained the softness of electric current decline.Present invention also offers a kind of manufacture method of fast recovery diode.

Description

Fast recovery diode and make the method for this diode

Technical field

The present invention relates to a kind of diode and make the method for this diode.

Background technology

Along with the development of power electronic technology, the application of various frequency changer circuit, chopper circuit constantly expands, no matter the major loop in these Power Electronic Circuit is the thyristor adopting commutation cutoff, or adopt the novel power transistor having self-switching-off capability, all need an in parallel with it and diode that reverse recovery time is shorter, with by the reactive current in load, suppress because of the instantaneous oppositely high voltage responded to of load current simultaneously.

Accordingly, the fast recovery diode that many moneys differ from one another is pushed to application market, HEXFRED of EMCON, IR company of the sonicFRD (FastRecoveryDiodes, fast recovery diode) of such as IXYS company, SPT+FRD, Infineon company of ABB AB etc.

Please refer to Fig. 1, it illustrates a kind of fast recovery diode of P-i-N structure, it comprises diode anode district 101, diode tagma 102 and diode cathode district 103.Be reach the effect that electric current is ended rapidly when reverse bias, generally can adopt and reduce the technology such as anode region hole injection efficiency and overall minority carrier life time control, to change the CONCENTRATION DISTRIBUTION of the charge carrier in diode tagma 102.But these technology are often difficult to make fast recovery diode obtain ideal trading off in parameter.Such as, the diode of P-i-N structure is shortened on reverse recovery time, but Reverse recovery (namely di/dt is too large) really up to the mark, thus too high Reverse recovery voltage can be caused, burn even if fast recovery diode itself does not puncture, also can produce harmful effect to practical application circuit.

Summary of the invention

The object of the present invention is to provide a kind of can the fast recovery diode of soft recovery and the manufacture method of this diode.

A kind of fast recovery diode, comprise a N-type highly doped silicon substrate, one first N-type doping semiconductor layer, one second N-type doping semiconductor layer, a diode anode layer, described first N-type doping semiconductor layer is between the second N-type doping semiconductor layer and N-type highly doped silicon substrate, and the doping content of described first N-type doping semiconductor layer is lower than the doping content of the second N-type doping semiconductor layer.

A manufacture method for fast recovery diode, comprising:

A N-type highly doped silicon substrate makes low-doped extension, to form one first N-type doping semiconductor layer;

Described first N-type doping semiconductor layer makes a place prolong, to form one second N-type doping semiconductor layer, the doping content of wherein said first N-type doping semiconductor layer is lower than the doping content of the second N-type doping semiconductor layer; And

Diode anode layer is diffuseed to form again at described second N-type doping semiconductor layer implanting p-type impurity.

Above-mentioned fast recovery diode and preparation method thereof is by the doping content of change first N-type doping semiconductor layer, to form " PNN-N+ " structure, wherein the doping content of the first N-type doping semiconductor layer is lower than the doping content of the second N-type doping semiconductor layer, so form a NN-knot.When described fast recovery diode is reverse-biased, due to the existence of NN-junction barrier, will the reverse extraction of electronics be hindered, thus improve the carrier concentration in this region, fast recovery diode is enable to provide enough carrier concentrations when Reverse recovery, to maintain the softness that electric current declines.

Accompanying drawing explanation

Fig. 1 is the schematic diagram of existing fast recovery diode.

Fig. 2 is the schematic diagram of the better embodiment of fast recovery diode of the present invention.

Fig. 3-8 is reverse recovery current oscillogram and the Reverse recovery voltage oscillogram of fast recovery diode of the present invention.

Fig. 9 is the flow chart of the better embodiment of the manufacture method of fast recovery diode of the present invention.

Embodiment

Please refer to Fig. 2, the better embodiment of fast recovery diode of the present invention comprises N-type highly doped silicon substrate 111,1 first N-type doping semiconductor layer 112,1 second N-type doping semiconductor layer 123, diode anode layer 134, and described first N-type doping semiconductor layer 112 is between the second N-type doping semiconductor layer 123 and N-type highly doped silicon substrate 111.The width of wherein said first N-type doping semiconductor layer 112 is 5 μm to 50 μm, doping content is 5e12/cm ³-5e14/cm ³.The doping content N of described second N-type doping semiconductor layer 123 _dformula (1) is met with the width d of the second N-type doping semiconductor layer 123:

wherein ε in formula (1) _rfor the dielectric constant of silicon, ε ₀for permittivity of vacuum, e refers to Single Electron electricity, V _rfor the reversed bias voltage normally worked, EBV is critical breakdown strength.

Described in upper, the width d of described second N-type doping semiconductor layer 123 then meets formula (2):

${\left(\frac{2{\mathrm{\&epsiv;}}_r{\mathrm{\&epsiv;}}_0}{e}\frac{V_R}{N_D}\right)}^{\frac{1}{2}}<d<\frac{{\mathrm{\&epsiv;}}_r{\mathrm{\&epsiv;}}_0{E}_{BV}}{{\mathrm{eN}}_D}---\left(2\right).$

Above-mentioned fast recovery diode passes through the doping content of change first N-type doping semiconductor layer 112, to form " PNN-N+ " structure.Wherein the doping content of the first N-type doping semiconductor layer 112 is lower than the doping content of the second N-type doping semiconductor layer 123, so form a NN-knot.When described fast recovery diode is reverse-biased, due to the existence of NN-junction barrier, will the reverse extraction of electronics be hindered, thus improve the carrier concentration in this region, fast recovery diode is enable to provide enough carrier concentrations when Reverse recovery, to maintain the softness that electric current declines.As can be seen from description above, as long as the first N-type doping semiconductor layer 112 is between the second N-type doping semiconductor layer 123 and N-type highly doped silicon substrate 111, and the doping content of described first N-type doping semiconductor layer 112 can realize lower than the doping content of the second N-type doping semiconductor layer 123 object maintaining the softness that electric current declines.

Please continue to refer to Fig. 3 and Fig. 4, it illustrates reverse recovery current oscillogram and the Reverse recovery voltage oscillogram of three kinds of fast recovery diodes, wherein curve A 1 represents that the second N-type doping semiconductor layer doping content is 3e14/cm ³, the first N-type doping semiconductor layer doping content is 5e14/cm ³the reverse recovery current oscillogram of fast recovery diode and Reverse recovery voltage oscillogram, curve B 1 represents that the second N-type doping semiconductor layer doping content is 3e14/cm ³, the first N-type doping semiconductor layer doping content is 3e14/cm ³the reverse recovery current oscillogram of fast recovery diode and Reverse recovery voltage oscillogram, curve C 1 represents that the second N-type doping semiconductor layer doping content is 3e14/cm ³, the first N-type doping semiconductor layer doping content is 5e13/cm ³the reverse recovery current oscillogram of fast recovery diode and Reverse recovery voltage oscillogram.The width of the second N-type doping semiconductor layer of above-mentioned three fast recovery diodes is 35 μm, and the width of the first N-type doping semiconductor layer is 25 μm.As can be seen from Fig. 3 and Fig. 4, the reverse recovery current softness of the third fast recovery diode above-mentioned and Reverse recovery voltage obtain improvement to a certain degree relative to the first and the second fast recovery diode.

Please continue to refer to Fig. 5 and Fig. 6, it illustrates reverse recovery current oscillogram and the Reverse recovery voltage oscillogram of other three kinds of fast recovery diodes, wherein curve A 2 represents that the second N-type doping semiconductor layer doping content is 1e15/cm ³, the first N-type doping semiconductor layer doping content is 2e15/cm ³the reverse recovery current oscillogram of fast recovery diode and Reverse recovery voltage oscillogram, curve B 2 represents that the second N-type doping semiconductor layer doping content is 1e15/cm ³, the first N-type doping semiconductor layer doping content is 1e15/cm ³the reverse recovery current oscillogram of fast recovery diode and Reverse recovery voltage oscillogram, curve C 2 represents that the second N-type doping semiconductor layer doping content is 1e15/cm ³, the first N-type doping semiconductor layer doping content is 5e14/cm ³the reverse recovery current oscillogram of fast recovery diode and Reverse recovery voltage oscillogram.Second N-type doping semiconductor layer of above-mentioned three kinds of fast recovery diodes and the width of the first N-type doping semiconductor layer are 5 μm.As can be seen from Fig. 5 and Fig. 6, the reverse recovery current softness of the third fast recovery diode above-mentioned and Reverse recovery voltage obtain improvement to a certain degree relative to the first and the second fast recovery diode.

In Fig. 7 and Fig. 8, curve A 3 represents that the second N-type doping semiconductor layer doping content is 2e13/cm ³, the first N-type doping semiconductor layer doping content is 5e13/cm ³the reverse recovery current oscillogram of fast recovery diode and Reverse recovery voltage oscillogram, curve B 3 represents that the second N-type doping semiconductor layer doping content is 2e13/cm ³, the first N-type doping semiconductor layer doping content is 2e13/cm ³the reverse recovery current oscillogram of fast recovery diode and Reverse recovery voltage oscillogram, curve C 3 represents that the second N-type doping semiconductor layer doping content is 2e13/cm ³, the first N-type doping semiconductor layer doping content is 1e13/cm ³the reverse recovery current oscillogram of fast recovery diode and Reverse recovery voltage oscillogram.Second N-type doping semiconductor layer of above-mentioned three fast recovery diodes and the width of the first N-type doping semiconductor layer are 50 μm.As can be seen from Fig. 7 and Fig. 8, the reverse recovery current softness of the third fast recovery diode above-mentioned and Reverse recovery voltage obtain improvement to a certain degree relative to the first and the second fast recovery diode.

As can be seen from description above, the doping content of the second N-type doping semiconductor layer of above-mentioned fast recovery diode need ensure that fast recovery diode is under its operating voltage, the width of depletion layer is less than the width of the second N-type doping semiconductor layer, fast recovery diode can not be made breakdown under the bias condition being less than rated voltage simultaneously.

Please refer to Fig. 9, the better embodiment of the manufacture method of fast recovery diode of the present invention comprises the following steps:

Step S51: make low-doped extension on N-type highly doped silicon substrate 111, to form one first N-type doping semiconductor layer 112, the width of wherein said first N-type doping semiconductor layer 112 is within the scope of 5 μm-50 μm, and doping content is at 5e12/cm ³-5e14/cm ³in scope.

Step S52: continue making place and prolong on the first N-type doping semiconductor layer 112, to form one second N-type doping semiconductor layer 123, the doping content N of wherein said second N-type doping semiconductor layer 123 _dand width d meets following formula:

${\left(\frac{2{\mathrm{\&epsiv;}}_r{\mathrm{\&epsiv;}}_0}{e}\frac{V_R}{N_D}\right)}^{\frac{1}{2}}<d<\frac{{\mathrm{\&epsiv;}}_r{\mathrm{\&epsiv;}}_0{E}_{BV}}{{\mathrm{eN}}_D},\frac{2{\mathrm{\&epsiv;}}_r{\mathrm{\&epsiv;}}_0{V}_R}{{\mathrm{ed}}^2}<N_D<\frac{{\mathrm{\&epsiv;}}_r{\mathrm{\&epsiv;}}_0{E}_{BV}}{ed},$ Wherein.

Step S53: diffuse to form diode anode layer 134 again at the second N-type doping semiconductor layer 123 implanting p-type impurity.

Certainly, after step S53, steps such as will carrying out such as carrier lifetime control, front metal and back metal of still needing.Because it is identical with existing diode, therefore do not repeat them here.

The foregoing is only preferred embodiment of the present invention, not in order to limit the present invention, all any amendments done within the spirit and principles in the present invention, equivalent replacement and improvement etc., all should be included within protection scope of the present invention.

Claims (1)

1. a fast recovery diode, comprise a N-type highly doped silicon substrate, one first N-type doping semiconductor layer, one second N-type doping semiconductor layer, a diode anode layer, described first N-type doping semiconductor layer is between the second N-type doping semiconductor layer and N-type highly doped silicon substrate, the doping content of described first N-type doping semiconductor layer is lower than the doping content of the second N-type doping semiconductor layer, and the width of described first N-type doping semiconductor layer is 5 μm to 50 μm, doping content is 5e12/cm ³-5e14/cm ³, the doping content N of described second N-type doping semiconductor layer _dand second the width d of N-type doping semiconductor layer meet formula wherein ε _rfor the dielectric constant of silicon, ε ₀for permittivity of vacuum, e refers to Single Electron electricity, V _rfor the reversed bias voltage normally worked, E _bVfor critical breakdown strength, the doping content of described first N-type doping semiconductor layer is 5e13/cm ³, the doping content of described second N-type doping semiconductor layer is 3e14/cm ³, the width of described first N-type doping semiconductor layer is 25 μm, and the width of described second N-type doping semiconductor layer is 35 μm.